(Electricity and Magnetism)
Four objects each with charge 1.2×10−4 C are located at the corners of a square whose sides are 2.1 m long.
1. Find the electric force on a charged object placed at the center of the square.
2. Find the total electric potential energy of the system consisting of the four charged objects.

Question

(Electricity and Magnetism)
Four objects each with charge 1.2×10−4 C are located at the corners of a square whose sides are 2.1 m long.
1. Find the electric force on a charged object placed at the center of the square.
2. Find the total electric potential energy of the system consisting of the four charged objects.

emmatassone · Answer

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As every object in the corner has the same charge and as they are equally far from that point , they do the same force to the object located in the center.
Try to prove it proposing the sum of forces of x and y axis and see what happens, you should get to zero as i said before.
In my drawing i supposed the object in the center had  the opposite charge that the object in the corner, but if it had the same charge the result would be the same.